Abstract:
Petrodiesel is an unsustainable and undependable fuel owing to its environmental concerns
and depleting reserves. Biodiesel is a sustainable alternative fuel to petrodiesel with a better fuel quality
and minimum environmental impacts. However, cost-effective biodiesel production requires the use
of a sustainable feedstock and process optimization. This study explored biodiesel yield optimization
from mixed microalgae oil (MO) and waste cooking oil (WCO). The use of mixed feedstock for
biodiesel production relievesthe rising demands; lowers feedstock costs; and improves the fuel quality,
engine performance, and pollutants emission characteristics. MO was extracted from dried microalgae
biomass by the Soxhlet method using hexane. The MO and WCO were purified and characterized, and
an oil blend with suitable properties (best in kinematic viscosity, density, higher heating value, and
acid value compared to other blends) was selected. The transesterification experiments designed by
central composite design were optimized using the response surface methodology. Experimental
results underwent regression analysis to develop a quadratic model equation for predicting the
optimum level of parameters and biodiesel yield. Model fitness and variables effects on biodiesel yield
were studied using analysis of variance. The optimization experiment achieved 98.82% oil conversion
rate at the catalyst loading of 2.0 w/v%, molar ratio of 12:1 v/v, reaction temperature of 60 ℃, and
reaction time of 100 min. A triplicate validation experiments achieved 97.72% conversion rate, which
is very close to the model predicted result (99.1%). Biodiesel from MO-WCO showed a better cetane
number (77.76), iodine value (12.90 gI2/100 g), acid value (0.049 mg KOH/g), HHV (43.25 MJ/kg),
kinematic viscosity (4.50 mm2
/s), pour point (–2.5 ℃), and flash point (180 ℃). In conclusion, the
study revealed that transesterification of blended MO-WCO led to a maximum biodiesel and the
reaction time and temperature were found to be the most significant factors affecting the yield of
AIMS Energy Volume 12, Issue 2, 408–438.
biodiesel. Furthermore, biodiesel from blended MO-WCO is a sustainable and environmentally
friendly alternative fuel source which can contribute towards a promising industrial scale biodiesel
production in the future.
